Autonomous underwater vehicle with current monitoring

Abstract

The present invention relates to an autonomous underwater vehicle (“AUV”) for monitoring underwater fluid currents by detecting electrical currents induced by the flow of a conductive liquid through the Earth's magnetic field. More particularly, the present invention relates to the gathering of data related to underwater fluid currents and the control of AUV motion during data gathering.

1. An apparatus comprising:
 a sealed hull having at least first and second electrodes; 
 a propulsion unit for moving the hull through a conductive liquid while the hull is submerged under a surface of the conductive liquid; and 
 a control system coupled to the electrodes and configured to
 monitor voltages at the electrodes, wherein the voltages are the result of the motion of the conductive liquid with respect to the magnetic field of the Earth; 
 control the propulsion unit such that the electrodes are moved along a reciprocating course during voltage monitoring, wherein the reciprocating course includes at least a one hundred eighty degree change in horizontal heading and a plurality of depths in the conductive liquid; and 
 wirelessly transmit signals representative of the motion of the conductive liquid, relative to a frame of reference that is fixed with respect to the surface of the Earth, within which the hull resides to a location remote from the hull while the hull is on the surface of the conductive liquid, wherein the control system is further configured to remove from the signals portions representative of the voltage generated by motion of the apparatus with respect to the magnetic field of the Earth and the voltage of the electrodes in a conductive liquid. 
 
 
     
     
       2. The apparatus of  claim 1 , wherein the control system controls the propulsion unit so that the hull moves along a reciprocating course having a vertical component. 
     
     
       3. The apparatus of  claim 2 , wherein the reciprocating course has a helical form. 
     
     
       4. The apparatus of  claim 1 , wherein the control system controls the propulsion unit so that the hull moves at a substantially constant speed. 
     
     
       5. The apparatus of  claim 1 , wherein the control system acquires data representative of the speed of the hull. 
     
     
       6. The apparatus of  claim 5 , wherein the control system acquires data representative of the orientation of the hull. 
     
     
       7. The apparatus of  claim 1 , wherein the propulsion unit includes at least one propeller. 
     
     
       8. The apparatus of  claim 1 , wherein the propulsion unit includes a buoyancy control to cause motion of the hull in response to changes in the buoyancy of the hull, and control surfaces being operable by the control system to control the direction of the hull while in motion. 
     
     
       9. An apparatus comprising:
 a sealed vessel for moving under the surface of the ocean; 
 at least two electrodes in communication with the ocean; 
 a controller located within the vessel and coupled to the at least two electrodes, wherein the controller is configured to:
 generate voltage data representative of voltages at the electrodes during motion of the vessel, wherein the voltages are the result of the motion of the ocean water with respect to the magnetic field of the Earth, and wherein the controller is further configured to remove from the voltage data portions representative of the voltage generated by motion of the apparatus with respect to the magnetic field of the Earth and the voltage of the electrodes in the ocean; 
 generate location data representative of the location of the vessel during generation of the voltage data; 
 generate motion data representative of the motion of the ocean water at locations represented by the location data, wherein the motion of the ocean water is referenced to the surface of the Earth; and 
 store the voltage data and location data in a memory; and 
 
 a propulsion unit coupled to the sealed vessel and electrically controlled by the controller to move the vessel along a reciprocating course under the surface of the ocean, wherein the reciprocating course includes at least a one hundred eighty degree change in horizontal heading and a plurality of depths in the ocean. 
 
     
     
       10. The apparatus of  claim 9 , wherein the controller is configured to transmit data representative of the voltage at the electrodes and location data to a location displaced from the vessel. 
     
     
       11. The apparatus of  claim 9 , wherein the propulsion unit includes at least one propeller. 
     
     
       12. The apparatus of  claim 9 , wherein the propulsion unit includes a buoyancy control to cause motion of the hull in response to changes in the buoyancy of the hull, and one or more control surfaces operable by the controller to control the direction of the hull while in motion. 
     
     
       13. The apparatus of  claim 9 , wherein the reciprocating course has a helical form. 
     
     
       14. A method for monitoring ocean currents, comprising:
 moving a sealed vessel that includes at least 2 electrodes along a reciprocating course under a surface of the ocean, wherein the reciprocating course includes at least a one hundred eighty degree change in horizontal heading and a plurality of depths in the ocean; 
 determining a first voltage difference between the electrodes at a first location along the course; 
 determining a second voltage difference between the electrodes at a second location along the course, wherein the first voltage difference and the second voltage difference are the result of the motion of the ocean water relative to the magnetic field of the Earth; and 
 generating a velocity signal representative of the horizontal velocity of the ocean water, with respect to a frame of reference that is fixed with respect to the surface of the Earth, at the second location, wherein portions of the velocity signal that are representative of the voltage generated by motion of the apparatus with respect to the magnetic field of the Earth and the voltage of the electrodes in the ocean are removed. 
 
     
     
       15. The method of  claim 14 , wherein the method of  claim 14  is repeated to generate a plurality of velocity signals representative of the horizontal velocity of ocean water at a plurality of ocean depths. 
     
     
       16. The method of  claim 15 , further comprising the step of storing the velocity signals in a memory. 
     
     
       17. The method of  claim 16 , further comprising the step of transmitting the velocity signals to a location displaced from the locations within the ocean at which the signals were generated. 
     
     
       18. The method of  claim 15 , further comprising the step of generating a visual representation of the current distribution within an area of the ocean based upon the velocity signals. 
     
     
       19. The method of  claim 14 , wherein the reciprocating course has a helical form.